Switch mechanism for an oil switch

ABSTRACT

The switch mechanism for an oil switch comprises a number of switch blades rigidly interconnected by a crossbar to form a single unit which is movable between open and closed positions with respect to stationary switch contacts. Both the switch contacts and switch blades are submerged in oil. The edges of the crossbar in the direction of movement of the unit are beveled, and there is an opening through the crossbar immediately below the level of oil so as to inhibit cavitation as the switch is operated.

United States Patent [191 Vantine [111 3,818,167 [45] June 18, 1974 SWITCH MECHANISM FOR AN OIL SWITCH [75] Inventor: Lynn R. Vantine, Tulsa, Okla. [73] Assignee: Sola Basic Industries, Inc.,

Milwaukee, Wis. [22] Filed: July 19, 1973 [21] Appl. No.: 380,826

52 us. (:1 200/150 (3 [51] Int. Cl. H0lh 33/68 [58] Field of Search 200/150 C, 150

[56] References Cited UNITED STATES PATENTS 2,100,753 11/1937 Schofield et 'al. 200/150 C 2,223,901

12/1940 Scarpa 200/150 C 3,739,115 6/1973 McClain et a]. 200/l50 C Primary Examiner-Robert S. Macon Attorney, Agent, or Firm-Smythe & Moore [5 7] ABSTRACT The switch mechanism for an oil switch comprises a number of switch blades rigidly interconnected by a crossbar to form a single unit which is movable be- 7 tween open and closed positions with respect to sta- 'tionaryswitch contacts. Both the switch contacts and switch blades are submerged in oil. The edges of the crossbar in the direction of movement of the unit are beveled, and there is an opening through the crossbar immediately below the level of oilso as to inhibit cavitation as the switch is operated.

6 Claims, 3 Drawing Figures 1 SWITCH MECHANISM FOR AN OllL SWITCH This invention relates to oil immersed electric switches, and more particularly to the movable switch blade structure of the switch mechanism.

A conventional oil switch for controlling the flow of electric current may comprise a plurality of switch blades which are movable individually or simultaneously into or out of contact with the corresponding plurality of fixed contacts. The contacts and the switch blades are both submerged in oil. When it is desired to construct an oil switch in which the movable blades operate as a unit, the individual switch blades must be rigidly interconnected to form such a unit. This is generally done by means of a rigid crossbar. In order that the unit have sufficient rigidity and strength, the crossbar must be of a sufficiently large size to perform these functions, and this large size is accompanies by a relatively great surface area. The movement of this crossbar through the-oil may produce a violence and agitation on the surface of the oil so that a quantity of the air which is in the space above the oil may become intermixed with the oil. This problem at the oil-air interface wherein air enters the oil is undesirable since the presence of the air within the oil may prolong an arcing between the contacts and the blades when the blades are opened. At the same time, an air space must be provided above the oil in order to accomodate any expansion of the oil due to temperature change.

One of the objects of the invention is to provide an improved switch blade mechanism for an oil switch.

Another of the objects of the invention is to provide a movable switch blade mechanism for an oil switch which eliminates the problem at the oil-air interface of air entering the oil.

According to one aspect of the invention, a switch mechanism for an oil switch may include a plurality of spaced stationary switch contacts submerged in oil contained in a casing with an air space at the top. A corresponding plurality of switch blades are rigidly interconnected by a crossbar into a single unit which is movable between opened and closed positions with respect to the switch contacts. The crossbar is substantially rectangular in cross section and is disposed with the longer dimension in the direction of movement of the switch blade unit between its open and closed position. The shorter dimension face is provided with a beveled surface, and there is an opening in the bar through the longer dimension faces below the level of oil in the casing. The combination of the beveled surfaces on the crossbar and the opening in the crossbar immediately below the surface of the oil will prevent air from entering the oil when the switch blades are being opened from the contacts, especially when the opening is rapid.

These and other objects, advantages and features of the invention will become apparent from the following description and drawings which are merely exemplary.

In the drawings:

FIG. 1 is a top plan view of an oil switch incorporating the mechanism according to the present invention with a major portion of the cover being removed to reveal the switch mechanism therein;

FIG. 2 is an elevational view of a switch mechanism taken in the direction of the line 2-2 of FIG. I; and

FIG. 3 is a perspective view in enlarged scale of the upper portion of the movable blade mechanism showing the opening and beveled edges on the crossbar.

In the various views and where appropriate, the same parts will be indicated by like reference symbols.

An oil switch incorporating the present invention is indicated generally at 10 in FIG. 1 and comprises a casing 11 filled with oil 12 and enclosed by a cover member 13.

Within the casing are three switch mechanisms each indicated generally at 14. Each switch mechanism comprises a plurality of fixed switch contacts 15 and a corresponding plurality of movable switch blades 16 which are rigidly interconnected by crossbar 17 to form a single movable unit. Blades 16 are also interconnected by a structural angle member 18. The blades 16, crossbar l7 and angle 18 define a single movable blade unit indicatedgenerally at 19 and which is pivotally mounted at 20. The unit 19 is connected through a suitable operating mechanism 21 as known in the art to to an operating handle 22. One form of operating mechanism can be similar to that shown in copending US. Pat. application Ser. No. 302,019, filed Oct. 30, 1972.

As can be seen in FIG. 2,-there is an air space 23 above the level of oil below cover 13 of the casing. The air space is necessary to accomodate expansion of the oil resulting from temperature change. However, the presence of the air in this air space produces problems at the oil-air interface'24. The movement of unit 19 within the oil produces a turbulence of oil at the level 24 and which will cause air to enter into the oil. The presence of air in the oil may result in prolonged arcing between the fixed contact and switch blade contacts when the contacts are being opened. To eliminate this problem, the crossbar 17, which is illustrated in greater detail in FIG. 3, has beveled ends 17A at its shorter dimension surfaces and these ends are positioned to move in the direction of movement of the switch blades between their open and closed positions. Also, preferably there can be a circular opening 26 through the opposed longer dimension faces 27 of the crossbar. The opening 26 is located immediately below the surface 24 of the oil as can be seen in FIG. 2.

The presence of opening 26 in the crossbar together with the beveled surfaces significantly reduces any turbulence or churning of oil at its surface so as to effectively prevent any air from entering the oil during movement of the movable units 19. It is particularly important to prevent the entry of air into the oil when the contacts are being opened since any air in the oil during this operation may prolong arcing.

In the embodiment shown, the beveled end 25 comprises a pair of beveled surfaces 28 which intersect at 29 to form a point, sharp line or radius.

It should be apparent that variations can be made in details of construction without departing from the spirit of the invention except as defined in the appended claims.

What is claimed is:

I. In a switch mechanism for an oil switch, the combination of a casing having oil therein, a plurality of spaced stationary switch contacts within said casing submerged in the oil, a corresponding plurality of switch blades movable between open and closed positions with respect to said switch contacts and submerged in the oil, a crossbar rigidly interconnecting said switch blades to define a single movale unit, said wherein said opening passes through opposed longer dimension facesof said crossbar.

v 4. In a switch mechanism as claimed in claim 1 wherein the beveled surface comprises a narrow apex.

5. In a switch mechanism as claimed in claim 1 wherein both edges of each shorter dimension face are beveled, the beveled, surfaces on each face meeting at a narrow apex.

6. In a switch mechanism for an oil switch, the combination of a casing having oil therein, a plurality of spaced stationary switch contacts within said casing submerged in the oil, a corresponding plurality of switch blades movable between open and closed positions with respect to said switch contacts and submerged in the oil, a crossbar rigidly interconnecting said switch blades to define a single movable unit, said crossbar having a substantially rectangular cross section and disposed with the longer dimension thereof in the direction of movement of the switch blade unit be tween its open and closed position, the shorter dimension spaces having a beveled surface thereon. 

1. In a switch mechanism for an oil switch, the combination of a casing having oil therein, a plurality of spaced stationary switch contacts within said casing submerged in the oil, a corresponding plurality of switch blades movable between open and closed positions with respect to said switch contacts and submerged in the oil, a crossbar rigidly interconnecting said switch blades to define a single movale unit, said crossbar having a substantially rectangular cross section and disposed with the longer dimension thereof in the direction of movement of the switch blade unit between its open and closed positions, the shorter dimension spaces having a beveled surface thereon, there being an opening in tHe crossbar immediately below the level of oil.
 2. In a switch mechanism as claimed in claim 1 wherein said opening is circular.
 3. In a switch mechanism as claimed in claim 1 wherein said opening passes through opposed longer dimension faces of said crossbar.
 4. In a switch mechanism as claimed in claim 1 wherein the beveled surface comprises a narrow apex.
 5. In a switch mechanism as claimed in claim 1 wherein both edges of each shorter dimension face are beveled, the beveled surfaces on each face meeting at a narrow apex.
 6. In a switch mechanism for an oil switch, the combination of a casing having oil therein, a plurality of spaced stationary switch contacts within said casing submerged in the oil, a corresponding plurality of switch blades movable between open and closed positions with respect to said switch contacts and submerged in the oil, a crossbar rigidly interconnecting said switch blades to define a single movable unit, said crossbar having a substantially rectangular cross section and disposed with the longer dimension thereof in the direction of movement of the switch blade unit between its open and closed position, the shorter dimension spaces having a beveled surface thereon. 